Proper Japanese Title: 水中騎士
Originally serialized in Ultra Jump, it was put on hiatus when the author began Gunnm: Last Order in the same magazine. A decade into that series, he left the publisher over a dispute and Aqua Knight has never been returned to.
— Description from Comic Vine community (comicvine.gamespot.com · https://comicvine.gamespot.com/aqua-knight/4050-103312/).